[libvirt] [PATCH v4 03/10] Refuse to reattach from vfio if the iommu group is in use by any domain

[Michal Privoznik]

On 14.11.2015 09:36, Shivaprasad G Bhat wrote:
> It is incorrect to attempt the device reattach of a function,
> when some other domain is using some functions belonging to the same iommu
> group.
> 
> Signed-off-by: Shivaprasad G Bhat <sbhat at linux.vnet.ibm.com>
> ---
>  src/util/virhostdev.c |   21 ++++++++++++++++++++-
>  1 file changed, 20 insertions(+), 1 deletion(-)
> 
> diff --git a/src/util/virhostdev.c b/src/util/virhostdev.c
> index de029a0..f24ccd8 100644
> --- a/src/util/virhostdev.c
> +++ b/src/util/virhostdev.c
> @@ -1590,18 +1590,35 @@ virHostdevPCINodeDeviceReAttach(virHostdevManagerPtr hostdev_mgr,
>                                  virPCIDevicePtr pci)
>  {
>      virPCIDeviceAddressPtr devAddr = NULL;
> +    bool usesVfio = false;
> +    char *drvPath = NULL;
> +    char *drvName = NULL;
>      struct virHostdevIsPCINodeDeviceUsedData data = {hostdev_mgr, NULL,
>                                                       false};
>      int ret = -1;
>  
> +    if (virPCIDeviceGetDriverPathAndName(pci, &drvPath, &drvName) < 0)
> +        goto out;
> +
> +    if (STREQ_NULLABLE(drvName, "vfio-pci"))
> +        usesVfio = true;
> +
>      virObjectLock(hostdev_mgr->activePCIHostdevs);
>      virObjectLock(hostdev_mgr->inactivePCIHostdevs);
>  
>      if (!(devAddr = virPCIDeviceGetAddress(pci)))
>          goto out;
>  
> -    if (virHostdevIsPCINodeDeviceUsed(devAddr, &data))
> +    if (usesVfio) {
> +    /* Doesn't matter which device. If any domain is actively using the
> +     * iommu group, refuse to reattach */

s/reattach/reattach./

And, does not matter right now, but maybe we will need to set
data.usesVfio = true; in this case. Currently, this will result in no-op

> +        if (virPCIDeviceAddressIOMMUGroupIterate(devAddr,
> +                                                 virHostdevIsPCINodeDeviceUsed,
> +                                                 &data) < 0)
> +            goto out;
> +    } else if (virHostdevIsPCINodeDeviceUsed(devAddr, &data)) {
>          goto out;
> +    }
>  
>      virPCIDeviceReattachInit(pci);
>  
> @@ -1614,6 +1631,8 @@ virHostdevPCINodeDeviceReAttach(virHostdevManagerPtr hostdev_mgr,
>      virObjectUnlock(hostdev_mgr->inactivePCIHostdevs);
>      virObjectUnlock(hostdev_mgr->activePCIHostdevs);
>      VIR_FREE(devAddr);
> +    VIR_FREE(drvPath);
> +    VIR_FREE(drvName);
>      return ret;
>  }
>  

And as you and Laine agreed, this is going to be turned into a list, so
this patch probably ends up being dropped anyway.

Michal